The answer to this question is B
Answer:
1. They must be removed before sister chromatids or homologous chromosomes can separate
Explanation:
During the S-phase of the cell cycle, not only does DNA have to be replicated, but also newly synthesized DNA molecules have to be connected with each other. This replicated DNA (sister chromatids) remain physically connected with each other from S phase until metaphase. This physical connection is called Sister chromatids cohesion.
Sister chromatid cohesion depends on COHESIN, a tripartite protein complex that forms a ring structure to hold sister chromatids together during mitosis and meiosis. Cohesin regulates the separation of sister chromatids during cell division, either mitosis or meiosis. This sister chromatid cohesion is essential for the biorientation of chromosomes on the mitotic or meiotic metaphase spindle, and is thus an essential prerequisite for chromosome segregation. Without the cohesion, sister chromatids would not be segregated symmetrically between the forming daughter cells, resulting in aneuploidy.
Cohesion is established during S-phase of DNA replication, and the cohesins hold the sister chromatid together after DNA replication until anaphase when the removal of cohesin leads to separation of sister chromatids (meiosis II and mitosis) and homologous chromosomes (meiosis I).
Outer most layer of the Earth is the crust
Answer:
Achondroplasia affects the long bones and individual has normal size, head and torso.
Explanation:
Achondroplasia dwarfism may be defined as the form of dwarfism in which the conversion of bone to cartilage is defected. This is the most common form of dwarfism.
Achondroplasia dwarfism mainly affects the long bones of an individual as there is problem in the conversion of cartilage to bone. The individuals have short arms and legs but they have normal head and torso size. The individuals has height around 4 feet.
